In instances in which a mobile terminal is subject to interference, a macro cell may find it to be difficult to reliably page the mobile terminal, such as for cell selection or cell reselection purposes. For example, in instances in which the mobile terminal is not only within the coverage area of a macro cell, but is also within the coverage area of a closed subscriber group (CSG) cell, such as a femtocell, of which the mobile terminal is not a member, the CSG cell may create relatively strong interference for the mobile terminal, thereby leading to difficulties in the macro cell successfully paging the mobile terminal. These difficulties are particularly problematic in an instance in which the mobile terminal is in the idle mode. In this regard, interference from a CSG cell may make it difficult to reliably have a successful cell search with regard to the primary and secondary synchronization signals so as to permit a macro cell to initiate a cell selection or cell reselection process. Additionally, strong interference from a CSG cell may also reduce the reliability with which a mobile terminal may receive paging and system information blocks (SIBs) while located within the coverage area of a CSG cell.
Almost blank subframes (ABS) are subframes in which a cell deliberately does not transmit any data except for the critical control data, e.g. synchronization signals, paging or system information, and reference symbols. ABSs can be used to e.g. protect the mobile terminals close to the CSG cells. For example, by using ABS in a CSG cell and coordinating the timing of the ABS with the macro cell, the network is able to arrange occasions during which a mobile terminal is able to function despite being close to an interfering CSG cell
For example, in order to reliably page a mobile terminal that is in the idle mode and that is otherwise subject to relatively strong interference from a CSG cell, the paging configuration of the network may be established such that the paging occasion (PO) of the macro cell aligns with the ABSs of the CSG cell. For example, the paging occasion in subframe 9 may be utilized by the macro cell in an instance in which subframe 9 is also the ABS of the CSG cell. In order to prevent interference between pages from the CSG cell and pages from the macro cell in subframe 9, a frame shift may be introduced between the CSG cell and the macro cell. However, this network configuration may make it challenging to attain the peak paging capacity, such as four subframes for a radio frame. For example, in an instance in which a frame shift of 10 milliseconds is introduced between the CSG cell and the macro cell, this network configuration may allow only one paging occasion every 20 milliseconds.
Another technique that has been proposed to remedy the adverse effects of interference from a CSG cell in regards to the paging of a mobile terminal in the idle mode is to provide for cross-subframe assignments in which a physical downlink control channel (PDCCH) resource on one subframe assigns a physical downlink shared channel (PDSCH) resource on another subframe. In accordance with this technique, a mobile terminal that is experiencing interference from a CSG cell may receive a PDCCH in a subframe that is an ABS subframe of the CSG cell. However, frequency domain multiplexing (FDM) coordination may be required to reduce the interference from the CSG cell to the resource blocks utilized by the macro cell for paging. Additionally, this approach may require changes to the radio access network so as to configure the cross-subframe related parameters and, in an instance in which the PDCCH reception occurs during a non-ABS subframe, to receive the PDCCH.